by John Bacon, USA TODAY

by John Bacon, USA TODAY

A Manhattan jury on Wednesday convicted Osama bin Laden's son-in-law of conspiracy to kill Americans and providing support for terrorists.

Sulaiman Abu Ghaith, who served as al-Qaeda's spokesman after the terror attacks of Sept. 11, 2001, is the most senior member of the terrorist organization to be tried in the United States. He drew attention around the world for a series of fiery videos praising the attacks and promising that more would be forthcoming.

Abu Ghaith "was more than just Osama bin Laden's propaganda minister," U.S. Attorney Preet Bharara said in a statement after the verdict was announced. "Within hours after the devastating 9/11 attacks, Abu Ghaith was using his position in al-Qaeda's homicidal hierarchy to persuade others to pledge themselves to al-Qaeda in the cause of murdering more Americans."

Bharara said he hoped the verdict brought "some small measure of comfort to the families of the victims" of terrorism.

Attorney General Eric Holder called the verdict "a major milestone in the government's unrelenting efforts to pursue justice against those involved with the September 11 attacks."

Abu Ghaith, 48, married bin Laden's daughter, Fatima. He testified during the three-week trial that he answered bin Laden's request in the hours after the attacks to recruit new followers for suicide missions. Nineteen recruits hijacked the four planes used on Sept. 11, 2001.

"The storm of airplanes will not abate," Abu Ghaith said in a video release a month after the attacks.

Defense lawyer Stanley Cohen downplayed his client's al-Qaeda role, saying he had no involvement or advance knowledge of any terrorist plots. Cohen said Abu Ghaith was speaking in his role as a Kuwaiti imam.

Assistant U.S. Attorney John Cronan, in his closing argument, emphasized the importance of Abu Ghaith's post-9/11 status.

"Going to that man was the very first thing Osama bin Laden did on Sept. 11 after the terror attacks," he said. "The defendant committed himself to al-Qaeda's conspiracy to kill Americans, and he worked to drive other people to that conspiracy."

The jury returned a guilty verdict on three charges: conspiracy to kill Americans, conspiring to provide support to al-Qaeda and providing support to al-Qaeda. Sentencing was set for Sept. 8. The charges carry a potential penalty of life in prison.

Abu Ghaith was captured in Jordan last year and brought to New York. He testified that he was not an al-Qaeda recruiter and claimed his role was a religious one aimed at encouraging all Muslims to rise up against their oppressors. He insisted he agreed to meet with bin Laden in a cave on the night of Sept. 11 out of respect for bin Laden's standing as a sheik.

"Despite knowing that he was responsible for the deaths of hundreds of Americans, you met with him to be polite, correct?" prosecutor Michael Ferrara asked on cross-examination.

"I didn't go to meet with him to bless if he had killed hundreds of Americans or not. I went to meet with him to know what he wanted," Abu Ghaith said.

Prosecutors used Abu Ghaith's testimony and closing arguments as an opportunity to re-show the image of the burning towers to jurors.

In his closing, Cronan used the defendant's testimony against him. "Accept it as totally true. If you do that, he's guilty," Cronan said.